1-Ethyl-4-[1-(1-phenylethylidene)hydrazin-2-ylidene]-3,4-dihydro-1H-2λ6,1-benzothiazine-2,2-dione

In the title compound, C18H19N3O2S, the thiazine ring adopts an envelope conformation, with the S atom displaced by 0.732 (1) Å from the other atoms of the ring. The phenyl ring is oriented at a dihedral angle of 79.33 (7)° with respect to the fused benzene ring. The conformations about the two double bonds in the R 2C=N—N=C(CH3)Ar grouping are Z and E, respectively. In the crystal, inversion dimers linked by pairs of C—H⋯O interactions generate R 2 2(8) and R 2 2(12) loops, as parts of infinite chains along the a-axis direction.